For a long time, the dominant conversation around internet censorship has focused on two of the practice's giants: Iran and China.

Arguably owners of the most sophisticated filtering methods, the criticism levied against these two countries has been deserved. And yet, the focus on them has largely been at the exclusion of other countries that also censor the web to varying degrees - including an increasing number of democracies.

In recent weeks, Turkey, Tunisia, and Australia have all made headlines for their various plans to introduce new filtering schemes. Though each country's plan differs, they all have similar focus: curbing access to obscene content.

But while blocking obscenity may reflect the will of the people, such filters nonetheless have implications for freedom of expression.

Australian ISPs 'aim to curb child sexual abuse'

In Australia, after several failed attempts by the government to introduce a mandatory filtering scheme, several Australian ISPs have taken matters into their own hands, blocking access to a list of 500 sites.

The ISPs will base their blacklists on a list maintained by the Australian Communications and Media Authority (ACMA), as well as - according to News.com.au - "child abuse URLs that are provided by reputable international organisations".

In 2009, a copy of the ACMA's blacklist was published by WikiLeaks, and was found to include the website of a Queensland-based dentist, a handful of Christian sites, and some YouTube videos - as well as adult sites deemed to be legal in Australia.

Such errors raise questions amongst free expression advocates about the lack of transparency in the process of determining which sites will be banned. There is also concern that there appears to be no appeals process by which to challenge sites banned by the ISPs.

Tunisia blocked pornography by court order

For years, Tunisia stood along with China and Iran as one of the world's most strict online censors. Following the January 2011 popular revolt, however, internet filtering became obsolete for a time.

Shortly thereafter, a military tribunal moved to block a handful of sites, including all individual Facebook profiles or pages.

The latest measure to block sites in Tunisia comes after a group of conservative lawyers filed a legal case to "impose the blocking of pornographic content". The Tunisian Internet Agency at first refused to implement the order and sought a stay of the ruling, but on June 13, the motion was denied and the Agency was forced to comply with the order.

The decision was met with derision by many Tunisians, some of whom protested on the grounds of personal freedom or concern that filtering any type of content would open the doors to further censorship; while others felt that the debate distracted from more important issues in the fledgling democracy. Still, some others were in support of the ban.

Turkey's four-pronged approach

Turkey's proposed filtering scheme has raised ire across the country, with citizens marching in the streets against censorship.

Though the scheme is meant to offer four opt-in layers of filtering - from "standard" to "children" - Turkish citizens realise they have plenty to lose. After all, the government has blocked YouTube and WordPress, among various other sites, for containing content deemed insulting to "Turkishness".

Meanwhile, Turkey's Law on the Internet #5651 allows any party to petition a court to block content for a range of reasons - including alleged defamation. Some Turkish analysts believe that the law is easily abused.

Furthermore, a 2009 report from the Organisation for Security and Cooperation in Europe highlighted that 80 per cent of Turkey's banned sites had been blocked at the behest of administrative decisions, rather than court rulings.

Though the new system's "standard" option will come without new filtering, there is no word as to whether already-blocked sites will remain banned.

Filtering is futile

While filtering - when conducted in the home or other private space - can be a good thing, such as preventing children from inadvertently accessing obscene or other undesirable content, government-level filtering does more harm than good.

Not only is it probable - and quite common - for "benign" sites to get caught up in content filters, blocking a certain type of content does not necessarily mean that such content ceases to exist; and in the case of child pornography, blocking may simply force such content "underground", to peer to peer and other private networks where perpetrators are more difficult to catch.

Filtering at the government or ISP level is costly, yet can be easily circumvented with minimal tech savvy, using widely available proxy tools.

Most problematically, setting a precedent of blocking websites simply makes it that much easier for a government or ISP to extend filtering as they wish.

While few might object to blocking child pornography, what happens when the filters go after politically sensitive content? Will anyone object then?

Jillian C York is the director for International Freedom of Expression at the Electronic Frontier Foundation in San Francisco.